Telephone-exchange switchboard signaling apparatus.



No. 633,403. Patented Sept. I9, 1899.

T. c. WALES, .IR. TELEPHONE sxcrmnes SWITCHBOARD SIGNALING APPARATUS.

(Application filed Jan. 23, 1899.)

(No Model.)

m: mums PETERS 410., PHOTO-LITHOY. wasnmar Erica UNITED STATES PATENT THOMAS C. \VALES, JR, OF NElVTON, MASSACHUSET S, ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

TELEPHONE-EXCHANGE SWITCHBOARD SIGNALING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 633,403, dated September 19, 1899.

Application filed January 23, 1899. Serial No. 703,142. (No model.)

To all whom it 'nmyconcer/t: central station a terminal switch-plug of a Be it known that I, THOMAS C. \VALES, Jr. connecting-cord circuit is inserted in a switchresiding at Newton, in the county of Middlesocket of the desired main substation-circuit, sex and State of Massachusetts, have inventand the call being sent in the usual way the 55 ed certain Improvements in Telephone-EX- call-bell at the substation is caused to ring; change Switchboard Signaling Apparatus, of but under these circumstances it is evident which the following is a specification. that until the subscriber thus signaled in This invention relates to the switching and response to such summons removes the reswitchboard signaling apparatus of a teleceiving-telephone from its support, taking it 60 phone-exchange central station, and more up for use, the exact conditions exist which particularly has reference to a certaim imhave been stated as necessary and suflicient proved arrangement of such switchboard-sigfor the operation of the disconnection-signal, nals, their controllingappliances and circuits, and as a consequence during this interval of and animpr ved system of operation whereby time a false signal is displayed to the central- .65 their indications are made positive, definite, station operator; or to state the facts otherand distinct. wise, the information conveyed by these sig- The invention is especially well adapted nals is not definite or positive, the operator for association with systems wherein the being required upon noticing the display of source of current-supply for signaling or for the signal associated with the called substa- 75 the telephone-transmitters, or for both, is tion to remember whether the said substation placed at the central station, and which, has merely failed to respond to the call or therefore, may be denominated central-enwhether the signal does, indeed, indicate a reergy systems. quest for disconnection.

In the practical operation of telephone cen- The object of the present invention is to 75 tral stations equipped with switchboards of bring about such a novel arrangement of the the modern relay-operated type ithas been signals, their circuit connections, and confound advantageous to place pairs of signals trolling devices that one of the said signals in juxtaposition before each operator, one shall in its display serve as a positive dissuch pair being associated with each complete connecting-signal and the other as an infor- 8o 0 switch-cord connection. These signals have mation-signal. Thus by this invention it is been intended to indicate the discontinuance provided that the constant or steady display of a conversation or the desire of a subof one of the signals may constitute an absoscriber for communication with the operator lute and definite order to detach the plugs and to inform the operator in general of the from the switch-sockets, the said signal being 85 5 condition of the substationapparatus. They operative from the substations of either of have been termed disconnecting or, more two united main lilies or circuits by the regenerally, supervisory signals, and each placement of the telephones of either or both has been so arranged in connection with other substations upon their respective suspensionapparatus that it will be exhibited when at switches. It is easy as a corollary of this 0 the close of a conversation the receiving-teleproposition to see that the act of lifting the phone is restored to its support at the correreceiver from the said suspension-switch and sponding substation. The conditions necesagain restoring it thereto several times in sary for the steady display of one of these sigrapid succession will effect an intermittent nals are that the terminal plug of the connecdisplay of the said signal, and that this also 5 tion-cord with which the signal is associated is an absolute signal and may constitute in shall be inserted in a switch-socket of a main all cases an indication that telephonic comtelephone-oi rcuitand that at the substation of munication with the operator is desired, as, such circuit the receiving-telephone shall for instance, would be the case if either of occupy its place of rest upon the switch-hook the two parties who had been conversing too provided for it. Now when a call-signal is wished immediately to speak with a third; to be transmitted to a substation from the and it is also provided that the exhibition of the other signal shall invariably and positively give the information that the telephone has not yet been removed from the suspension-switch at the called substation, while of course its disappearance gives the converse information.

Although I have shown but one plug-andcord circuit, it is of course to be understood that each operator is supplied with a number of these sufficient for the service.

The invention will be more fully understood by reference to the drawingaccompanying this specification, wherein I have shown in diagram a system embodying the same.

Referring to said drawing, L and L are main telephone-substation circuits converging from substations S S to a central station 0, a b and a 5 indicating the main conductors of the said circuits, respectively. The substation arrangement and the normal central-station arrangement of both circuits is of a standard central-energy type and is well understood. Briefly, there is at the substations a call-bell c, a condenser is, an induction-coilI, with primary and secondary windingsp and s, a suspension-switch H, a transmitting-telephone T, and a receiving-telephone t. Normally the receiver is hung upon the hook of the suspension-switch, and the circuit leads from conductor a through the call-bell and condenser to conductor b, the presence of the condenser making the circuit conductively discontinuous and preventing the flow ofcurrent. lVhen' the receiver is taken from the hook,a conducting-path is closed around the condenser and the current flows and operates the call-signal at the central station. At the same time a short local inductive circuit is established which includes the transmitter T and the condenser, so that'the operation of the said transmitter produces variations of potential between its terminals, and consequently waves in the said local circuit, which, by means of the induction-coil, propagate themselves in the main circuit in the form of voice-currents.

The conductors of the substation-circuits at the central station are led normally through contacts 00:00 of the usual cut-ofi relay 0'', after which conductor 5 is shown as being grounded at G, while conductor Ct continues through the call-signal relay r controlling the call-signal lamp 2, and to one pole of the universal battery, the other pole of which has among other-connections one with a ground terminal G The call-signal lamp .2 is shown as being in a ground branch a of this circuit, but of course may be in any local circuit controlled by the said relay.

J J are branch terminal spring-jacks or s'witch-sockets,whereby the several lines may be united to one another or to the operators apparatus through the intermediation of the plug-and-cord connection M, and the testrings m of these sockets are connected by a conductor 2 through the coils of the cut-off relay 1' to ground.

M represents the plug-t-tnd-cord switch coir nection as awhole, P the answering-plug, and P the calling-plug. Both plugs have a tipcontact 19 and a forward-sleeve contact 19 adapted to engage, respectively, the contactsprings j j of the switch-socket when the plug is thrust thereinto and a rearward -sleeve contact 19 adapted to register with the testring m of the said socket.

N is a split repeating induction-coil, with windings 7 and'S on one side and windings 9 and 10 on the other side of the battery B, the inner ends of windings 7 and 8 being united to one pole and the inner ends of windings 9 and 10 being similarly united to the other pole of said battery.

The plug-and-cord connection M comprises two main-circuit conductors 3 and 4 and one local-circuit conductor 12, the conductor 3 beingin each plug united to the tip, conductor 4 to the forward-sleeve, and conductor 12 to the rearward-sleeve contacts. From plug P the conductors 3 and 4 lead to the outward ends of the repeating-coil windings 7 and 9, respectively, and are united thereto, and from plug P the said conductors extend to and are connected similarly with the outer ends of windings 8 and 10. This arrangement divides the switch-cord main conductors into two sectional loops, each extending from the tip-contact to the forward-sleeve contact of its own plug, through two windings of the inductioncoil, and through the battery B, which, being in a bridge between the conductors 3 and 4, is thus common to both" loops, which, moreover, are inductively united by the repeatingcoil.

R and R are relays included in the sectional loops of the plugs P P respectively, and in the main telephone-circuits L L when the said plugs are placed in the switch-sockets J. Thus as soon as the telephones at the substations of such circuits are lifted from their suspension-switches, the plugs being placed in their switch-sockets, a strong current flows through the circuits and the relays R R included therein, exciting the latter and bringing about the forward motion of their armatures 17 andlS, respectively, as hereinafter described. It is obvious then that the suspension-switch of each substation controls the relay included in the main circuit of said substation, and then when the receiving-telephone is replaced on the hook of such switch the circuit will be restored to its conductively discontinuous condition, so

that the attractive power of the relay will cease, allowing the armature to fall back, and it is also evident that by repeating the operation of removing and replacing the receiver several times in rapid succession or (which amounts to the same thing) moving the suspension-switch up and down several times the armature of the relay will be successively attracted and retracted and will oscillate between its front and back stops.

T represents the operators telephone in- IIC strunlcnts and may be bridged between the switch-cord main conductors in series, if desired, with the condenser 7: by the aid of a listening-key, in the usual manner.

K is a generator supplying call-currents, and K a call-key associated with the cordcircuitM, whereby outgoing call-signals may be transmitted over the circuit L of a desired substation S for the operation of the callbell there.

R is the switching-relay, having an armature 19 and two reinforcing exciting-coils w and 3 f and f are artificial resistances to avoid short-circuiting of the current. a is the supervisory disconnecting-signal, and o the information-signal, these signals being preferably glow-lamps. Said switching-relay R which in a manner presently to be described aids the main relays-R R in actuating and differen tiatiug the lamp-signals n and 0 and which when brought into operation acts to open certaincontrolling-circuits andtoclose others, is so designed or adjusted in a manner well understood by those skilled in the art that the normal current through either windingw or y isinsufficientfor its operation; but when the normal current passes through both windings w and y simultaneously the relay-magnet becomes sufficiently excited and is able to attract the armature 19 to its forward position. lVhen the armature is once attracted, however, the current through either winding alone is sufficient to sustain the same, and consequently the connection thereof with its frontcontact stops. The excitingcoil 20 of the switching-relay R is in a local circuit associated with the answering-plugin sequence with the lamp-signal thereof, and exciting-coil y is in a shunt-circuit controlled by both main-line relays and adapted to be established around the said lamp-signal under certain conditions, all as will more fully be hereinafter explained.

The local circuit 12, associated with plug P, extends from the battery-main at point 13 through the disconnection-signal n and the winding 1!; of the switching-relay R to the rear-sleeve contact of the plug, while that associated with plug P extends from the same or similar point 13 through the information signal 0 and the resistance f to the rearsleeve contact of plug P Both of these circuits are closed (when their associate plugs are placed in the main-line switch-sockets) through the test-ring conductors 2 and the cutoff relays 0'. Hence the act of inserting the plug operates the cut-off relay.

Three shunt-circuits 'l), q, and e are associated with the signals a and 0, and as portions of the same conductors are utilized in all of the said shunts the circuit of each is indicated by its characteristic letter placed at intervals throughout the circuit. Two of these shunt-circuits L' and q belong to signal 01 and the shunt-circuit ebelongs to signal 0.

The shunt n extends from point 14 of the local. conductor 12 of plug P on one side of the lamp or, through the contacts 21 and 17 of relay R, conductors o and o back and armature contacts and 10 of switching-relay R conductor 1)", resistance f, junctionpoint 15, conductor r, to the point 25 on the other side of the lamp. Since the local current which flows through winding 20 of the relay R is not strong enough to effect the attraction of the armature 19 thereof, the said armature remains on its backstop, maintaining the shunt-circuit 'closed there, and since the said circuit is closed immediately when the plug P is inserted in its socket to answer a call at the contact 21 of relay R, which then becomes excited, the signal a is not displayed, the shunt U being established around it from the beginning of the operation. Until connection is made by the plug P with the wanted line and the call sent thereover and responded to by the substation thereof the shunt n remains closed around the signal 11, and it (and consequently the said signal) is controlled by the relay B only. The action of this shunt-circuit prevents the display of the disconnecting-signal when the answeringplug P is inserted into a jack J of the callingsubscribers line.

The shunt (1 may be traced as follows: from the same starting-point 1-t on one side of the lamp in, by conductor q, contacts 21 and 17 of relay R, conductor g the armature and fixed contacts 18 and 22 of relay R conductor (1 second exciting-coil y of switching-relay R conductor q, junction-point 15, conductor g to the point 25 on the other side of the lamp. This shunt q, being in part controlled by the relay R cannot close until the said relay, subsequent to the connection of the second plug and line, becomes excited. \Vhen answering the call which has been sent, the suspension-switch is operated at the substation S and closes the circuit L allowing the current of the battery B to flow therein. When, however, this is done, the armatures of both relays R and R are attracted, closing the shunt-circuit (1 through both sets of contactpoints, so that from this period of the operation the shunt q is established around the signal it and is controlled by both relays, and consequently can be operated by the switch at both stations; but as the said second shunt leads through winding 3 of the switch-relay the said relay now becomes fully excited and attracts its armature away from the back contact 23, thus opening the shunt 1). action of this second shunt-circuit prevents the display of the d isconn ecting-signal n when the plug P is inserted into jack J of the calledsubscribers line.

The shuntcircuit 6 belongs to the information-signal 0 and is adapted for establishment around said signal in the local circuit associated with the calling-plug and governs the operation of the signal. It being desired that signal 0 shall be displayed after the plug B is inserted into the socket of the wanted line and until the call transmitted to the substa- The tion thereof is attended to, the said shunt e is so arranged that it does not close and extinguish the signal until the telephone at the desired substation is taken up for use. It extends from the point 15 on one side of that signal to the point 26 on the other by way of conductor 6, resistance f, conductor 6 armature 19 of relay R front contact 24 thereof, and conductor 6 This shunt-circuit is normall y disestablished and remains so when the plug P is inserted in the socket J. Consequently the lamp 0 is lighted as soon as the said plug is inserted and its local circuit thereby closed to earth through the cut-off relay. While it remains lighted the operator knows that the telephone-receiver has not been removed from the switch at the substation S When the telephone is displaced therefrom, the circuit L closed byvt-he switch, and the relay R excited, the switch-relay also becomes operative, as alreadystated, and besides opening the first shunt at 23 closes the third shunt at 2i. The lamp 0 is thus extinguished, and having by the disappearance of its light informed the operator that the substation-receiver has been taken up for use it has no further function or office during the pendency of this particular communication and remains extinguished; but the other signal n being operative from both substations when either substation-telephone is replaced on its switch the armature of the corresponding relay falls back, opens the shunt-circuit q, and exhibits the disconnectiousignal.

Should either substation desire to attract the attention of the central-station operator prior to the termination of the message, this can be done by-alternately elevating and depressing the switch H repeatedly, and thus intermittentlyopening the main circuit. The effect of this is the oscillation of the armature of relay R or R as the case may be, and a flash signal of lamp "n. This does not affect the shunt e around lamp 0 or the lamp 0 itself, because though the circuit through the winding y of the switch-relay is opened the current in the upper winding is strong enough to maintain the magnetization and to sustain the armature 19 in its forward position,though not in the first place to attract it thereto.

When the substations have sent the disconnecting-signal by replacing their telephones on their switches, the plugs P and P are withdrawn from the sockets and all appliances associated with the switch-cord circuit assume their normal state.

Having thus fully described the invention and its operation, I claim- 1. In a telephone-exhange system, the combination of two telephone-substation circuits united by switch apparatus at a central station for through communication; a switch at the substations of said circuits controlling the electrical condition thereof; a supervisory signal at the central station associated with the said through circuit; and two relays one for each component circuit, both controlling the said supervisory signal, and responsive each to the action of. the switch at the substation of its respective component circuit.

2. The combination in atelephone-exchange switch apparatus, with aswitch-cord connection having a switch-plug at each terminal for uniting two substation-circnits, a supervisory signal associated with one of the said plugs, a shunt-circuit therefor governing the display thereof, all at a central station; and a suspension-switch at the substations of the said two circuits; of two relays associated with the said switch-plugs respectively, and connected in the main circuits of the said switch-cord, both of the said relays being organized to control the said supervisory-signal shunt-circuit, and to respond to the operation of the substation suspension-switches of the circuits with which their associated plugs are respectively connected.

3. In a telephone system and switching apparatus, two main circuits extending respectively between independent substations and the central station, and provided at the latter with switch-sockets; a switch-cord circuit connection uniting the said circuits for through communication, having its terminal switch-plugs placed in the switch-sockets of the calling and called circuits respectively; two relays, one in each main circuit; a supervisory signal associated with the callingcircuit switch-plug; a shunt-circuit governin g the display of said signal and controlled by the substation apparatus of the calling main circuit through the relay thereof; a second shunt-circuit for the said signal controlled by the substation apparatus of both main circuits through their respective relays; means for establishing the first shunt-circuit when connection is made between one of the said plugs and the calling main circuit; and means for establishing the second shunt-circuit and disestablishing the first,when switch connections having been made between the remaining plug and the called main circuit, a call-signal is transmitted thereover and responded to; substantially as set forth.

4. In a telephone switchboard apparatus, a sectional switch plug and cord connection circuit having main and local circuit conductors a supervisory signal connected with the local circuit thereof; two relays associated with the sectional main circuits of the two terminal plugs respectively, of said switch-cord connection; a shunt-circuit for the said signal controlled by one of the said relays; a second shunt-circuit therefor, controlled by both of the said relays; and a switch-relay operated by the closing of the second shunt, and adapted thereupon to open the first; substantially as and for the purposes specified.

5. The combination in a telephone exchange system, with two main substation-circuits, each having a switch controlling the electrical condition of the circuit at the substation, and switch-sockets at the central station; and a plug and cord switch connection circuit therefor; of two determinate and absolute signals associated with the said switch connection, one being responsive to the initial operation of the substation switch of the called substation and adapted to indicate the said operation; and the other being responsive to every operation of the switch at the calling substation, and to every subsequent operation of the called station, and adapted to indicate a desired disconnection; substantially as specified.

6. In a telephone-exchange and switching system the combination of a switch connection comprising a cord-circuit having terminal switch-plugs P P at its ends, and containing two main-circuit conductors extending between the plugs and divided into two sectional loops by a battery-bridge, and the conductors of two local circuits, one associated with each loop; a supervisory disconnecting-signal in the local circuit of the plug P; an information-signal in the local circuit of the plug P and two relays in the maincircuit sectional loops respectively; with a shuntcircuit governing the disconnectingsignal and controlled by one of the said relays; a second shunt-circuit for the said signal controlled by both relays; an independent shunt-circuit governing the display of the said information-signal; and a switching relay operated by the closing of the second shunt-circuit, and adapted thereupon to open the first shunt-circuit around the disconnecting-signal, to maintain the control of said sig nal by the relays associated with the main loops of both plugs, and to close and maintain closed the independent shunt-circuit of the information-signal, substantially as set forth.

7. The combination in a telephone switch apparatus, substantially as hereinbefore set forth,of a switch-cord having terminal switchplugs P P and containing two main-circuit conductors divided centrally into two sectional loops by a battery-bridge, and the conductors of two local circuits, one associated with each loop; a disconnecting-signal in the local circuit of plug P; an information-signal in the local circuit of plug P two relays It, R in the said main-circuit sectional loops respectively; a shunt-circuit governing the display of the disconnectingsignal and controlled by the relay R; a second shunt-circuit also governing the said signal, controlled by both relays; a third shunt-circuit governing the display of the information-signal; and a switching-relay with two independent exciting-coils contained respectively in the local signal-circuit of plug P, and in the second shunt-circuit, and adapted to attract its armature only when the said two coils reinforce one another, but to maintain the said attraction under the magnetizinginfiuence of either winding alone, the said switching-relay being thereby adapted to respond to the closing of the second shunt-circuit, and thereupon to open the first shunt-circuit and to close the third shunt-circuit.

S. The combination in a plug and cord switchboard connection comprising main and local circuits, of a disconnecting-signal in the local circuit ofone plug; an information-signal in the local circuit of the other plug; two relays in the main circuits of the two plugs respectively; a double-wound switching-relay; ashunt-circuit around the disconnectingsignal leading through the back contacts of the said switching-relay, and the contents, of one of the said main-circuit relays; a second shunt-circuit around the said disconnectingsignal extending through the contact-points of both main-circuit relays and one winding of the switching'relay; and a shunt-circuit for the informationsignal, extending through the front contacts of the said switching-relay; substantially as set forth.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 18th day of January, 1899.

THOMAS C. WALES, JR.

Witnesses: GEo. WILLIs PIERCE, JOSEPH A. GATELY.

Corrections in Letters Patent No. 633,403.

It is hereby certified that in Letters Patent No. 638,403, granted September 19, 1899, upon the application of Thomas 0. Wales, Jr., of Newton, Massachusetts, for an improvement in Telephone-Exchange Switchboard Signaling Apparatus, errors appear in the printed specification requiring correction, as follows: On page 5, lines 77 and 81, the word around should read round, same page, line 79, the Word contents should read contacts, and same page and column, in line numbers the numeral 80 should read '75; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed, countersigned, and sealed this 10th day of October, A. 1)., 1899.

[SEAL] WEBSTER DAVIS,

Assistant Secretary of the Interior.

, Oountersigned:

C. H. DUELL,

Commissioner of Patents. 

